I don't think Natasha was saying *anything* specifically. Rather, it was a test, with the goal being to goad Tony into doing *something*. What he chose to do would be the indicator.

Given that his response wasn't "party and get plastered" or "hide in my room getting drunk" or, yes, "hop into bed with Pepper like there's no tomorrow", but "suit up and pilot-while-drunk amidst bystanders," he did indeed fail big time. That's why Nick Fury showed up personally the next day.